Transcript Solar System Overview-Sec.1

The Solar System
Earth Science
Chapter 17
Sections 1-2
Solar System
• The sun and all things orbiting around it,
including the eight major planets, their
satellites, and all the smaller pieces such as
asteroids, meteoroids, and comets.
Not to scale
Image taken from:
http://asm.arc.nasa.gov/Gallery/images/generic/LG_Capableofeverything.jpg
Formation of the Solar System
Formed around 4.6 billion years ago
Solar Nebula
Huge cloud of gas and dust that collapsed
into a flattened disk
Disk
Sun formed at the center of the disk while
other objects (planets, moons, etc.) formed
from the whirling material of the disk
Solar System
Much of the material was cleared away. The
Sun, planets, and other objects remained
Images taken from:
http://astronomyonline.org/SolarSystem/SolarSystemFormation.asp
Planet
• Derived from a Greek word
that means “wanderer”
• A major object which orbits
around a star
• In our solar system, there are
eight such objects which are
traditionally called “planets”
Planet Classifications
• Terrestrial Planets
(inner planets)
– Mercury, Venus, Earth, Mars
– closest to the sun
– composed primarily of rock and
metal
– have deep atmospheres (except
Mercury), solid surfaces, no
rings, & few satellites
• Gas Planets
(outer planets)
– Jupiter, Saturn, Uranus,
Neptune
– composed primarily of hydrogen
& helium
– have deep atmospheres, rings, &
many satellites
Other Planet Classifications
• Three dwarf planets:
- Ceres
- Pluto
- Eris
• Inner and Outer planets separated by
Main Asteroid Belt
• Beyond orbit of Neptune is the Kuiper
Belt- small icy bodies
Orbit
• The path of an object in space as it travels around another
object
• Planets orbit around the sun in an elliptical (flattened
circle or oval) path; proposed by Johannes Kepler 
Kepler’s 1st Law
• Due to the gravitational attraction, a planet’s (or other
object’s) speed increases as it approaches the sun
• Planetary Motion
Not to scale
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
What do you think is the relationship
between a planet’s orbit and a “year?”
Orbit
• Ellipse- a slightly flattened circle or
oval
• Perihelion- the point at which a planet is
closest to the Sun
• Aphelion- the point at which a planet is
furthest from the Sun
• Figure 17.6 page 410
Orbit
• Orbital velocity- the speed at which a
planet travels in its orbit
• Planet moves fastest- perihelion
• Planet moves slowest- aphelion
• Greater gravitational attraction
between objects that are closer
Mass vs. Weight
Mass
Weight
• a measure of how much
matter an object is made of
• does not change, regardless
of where something or
someone is
• the force of gravity on an
object
• equal to the mass of the
body times the local
acceleration of gravity
Why do you
think the
person’s
weight is
less on the
moon?
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
Mass = 59 kg
Mass = 59 kg
Weight = 579 N
Weight = 96 N
http://www.exploratorium.edu/ronh/weight/index.html
Rotation vs. Revolution
Revolution
Rotation
•
•
•
the movement or path of the
earth or a heavenly body turning
on its axis
equivalent to one “day”
Earth rotates at a speed of
around 1,670 km/hr or 1000
mi/hr
The Earth
animation is
not rotating
in the
correct
direction;
it should be
rotating
from west to
east
•
•
•
•
the motion of one body around
another, such as Earth orbiting
around the sun
also known as an orbital period
equivalent to one “year”
Earth revolves at a speed of around
107,000 km/hr or 67,000 mi/hr
Sun
Tips for remembering:
rotation occurs in one day; day has three letters and rotation has three syllables
revolution occurs in one year; year has four letters and revolution has four syllables